In Phase 1, measuring and characterizing glucose oscillations in yeast cells immobilized on the surface of a glucose sensor was completed. Using this as a model, it was postulated that within the subcutaneous environment, cells (e.g., fibroblasts, adipocytes) would be in close proximity to the surface of the glucose sensor thereby mimicking the in vitro environment of the yeast cells on the surface of the glucose sensor. A 12- hour clinical study was completed wherein glucose measurements within interstitial fluid were highly correlated with reference glucose measurements. Moreover, measurements of glucose oscillations within subcutaneous tissue showed clear differences between normal subjects and those with type 1 and type 2 diabetes. Further studies in Phase 2 are aimed at building a data base of measurements, over longer time periods, to provide the means for characterizing different states of glycemia along the continuum from normal to impaired glucose tolerance to type 2 diabetes. Information gained from human studies in Phase 2, could provide the means of controlling an insulin pump based on periodic changes in cellular glucose metabolism, rather than relying solely on peripheral fingerstick blood glucose measurements for calibration purposes. Continuous glucose monitoring is an evolving, revolutionary technology that promises to improve the quality of life for millions of people with diabetes. In order to realize its full potential, more accurate devices that can be used for diagnosis and control, by providing physiological feedback to an insulin pump, are required. Measuring subcutaneous metabolic oscillations of glucose could provide a missing link for insulin pump feedback control, more accurate glucose measurements and novel methods for diagnosing stages of impaired glucose tolerance and insulin resistance. Measuring and characterizing aberrations in glucose metabolism within interstitial fluid and correlating them to known defects in glucose metabolism could be a major leap forward in diabetes management and provide an inexpensive tool for discovering new insights into the genetic and molecular origins of insulin resistance. The proposed Phase 2 research may result in a CGM system that reduces the need for frequent fingerstick blood glucose re-calibration eventually leading to a user calibration-free CGM that can be interfaced with an insulin pump to form an artificial pancreas.